Industrial controllers are special purpose processing devices used for controlling (e.g., automated and semi-automated) industrial processes, machines, manufacturing equipment, plants, and the like. A typical controller executes a control program or routine in order to measure one or more process variables or inputs representative of the status of a controlled process and/or affect outputs associated with control of the process. Such inputs and outputs can be digital and/or analog. A typical control routine can be created in a controller configuration environment that has various tools and interfaces whereby a developer can construct and implement a control strategy using industrial and conventional programming languages or graphical representations of control functionality. Such control routine can be downloaded from the configuration system into one or more controllers for implementation of the control strategy in controlling a process or machine.
Measured inputs received from a controlled process and outputs transmitted to the process can pass through one or more input/output (I/O) modules in a control system. Such modules can reside locally or remotely from the controller. Inputs and outputs can be recorded in I/O memory. The input values can be asynchronously or synchronously read from the controlled process by one or more input modules and output values can be written directly to memory by a processor for subsequent communication to the process by specialized communications circuitry. An output module can interface directly with a controlled process by providing an output from memory to an actuator such as a motor, drive, valve, solenoid, and the like. During execution of the control routine, values of the inputs and outputs exchanged with the controlled process can pass through memory. Values of inputs in memory can be asynchronously or synchronously updated from the controlled process by dedicated and/or common scanning circuitry. Such scanning circuitry can communicate with input and/or output modules over a bus on a backplane or network and asynchronously or synchronously write values of the outputs in memory to the controlled process. The output values from the memory can be communicated to one or more output modules for interfacing with the process.
Industrial controllers can communicate with databases, for example to store and/or retrieve data. Conventionally, database communication is accomplished by continuously polling automation devices and sampling data to determine if the automation device includes data that needs to be written to a database. Alternatively, an application could wait to be messaged a controller indicating that it has data that should be retrieved and written to a database or that desires to obtain data from the database. An industrial protocol such as CIP (Control and Information Protocol) is conventionally employed to poll, message, retrieve and/or receive data from the automation layer, which is subsequently presented to a database. However, all transmissions such as reads and writes are limited by proprietary industrial control protocol (e.g., CIP—Control and Information Protocol) connection size (e.g., 512 bytes). Furthermore, all requests transmitted in an industrial protocol are first routed to an Ethernet card or box that converts the requests and transmits them to a database.